Automatic speed changer

ABSTRACT

A second planetary gear unit PR and a clutch C 1  for outputting reduced speed rotation are located on one axial side of a first planetary gear unit PU, with an output unit located therebetween. A clutch C 2  which connects/disconnects an input shaft  2  to/from a sun gear S 2  of the planetary gear unit PU and a clutch C 3  connects and disconnects the input shaft to/from a carrier CR 2  of the planetary gear unit are on the other axial side of the first planetary gear unit PU. Compared with a transmission wherein a clutch C 2  or clutch C 3  is located between the second planetary gear unit PR and the planetary gear unit PU, the second planetary gear unit PR and the first planetary gear unit PU can be located closer together, and a member which transmits the reduced speed rotation can be made shorter. Further, compared to the case wherein, for example, the clutches C 1 , C 2 , C 3  are located together on one axial side, oil supply to their servos is simplified.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application (35 USC 371) ofPCT/JP2003/017066 and claims priority of Japanese Application No.2002-279860 filed Sep. 25, 2002.

TECHNICAL FIELD

The present invention relates to an automatic transmission mounted on avehicle, and more specifically, it relates to the design of an automatictransmission wherein multiple speed levels are established by input ofreduced speed rotation into one of the rotatable components of aplanetary gear unit.

BACKGROUND ART

Generally, a vehicular automatic transmission comprises two linkedplanetary gear units, and planetary gearing for reducing speed of therotation received from the input shaft (for example, see JapaneseUnexamined Patent Application Publication No. 4-125345). Such atransmission achieves, for example, six forward speeds and one reversespeed, by input of reduced speed rotation from the planetary gearing viaa clutch to, for example, one rotary component of a planetary gear unitthat has four rotary components. Further, in the case of fifth speedforward, for example, when the rotation of the input shaft issimultaneously input into two of the rotary components of the planetarygear unit by engaging two clutches, this fifth speed forward is adirectly coupled state, with rotation similar to that of the input shaft(see Japanese Unexamined Patent Application Publication No. 2000-274498,for example).

The above-described automatic transmission comprises two clutches forinput of the rotation of the input shaft into two of the rotarycomponents of the aforementioned planetary gear unit, and planetarygearing for reducing the speed rotation input into the rotary componentsof the planetary gear unit. However, if those two clutches or the oilservos that control the engagement of those clutches are located betweenthe planetary gear unit and the speed-reduction planetary gearing, theelement(s) for transmitting the reduced speed rotation of thisspeed-reduction planetary gearing to the rotary components of theplanetary gear must be axially lengthened.

The axial lengthening of the element(s) that transmits the reduced speedrotation means that the unit transmitting a large torque is elongated,and an elongated unit that can withstand the large torque requireselongation of a relatively thick material, preventing a compactautomatic transmission. Further, the weight of such a unit would beheavier, and not only would a lightweight automatic transmission becomeimpossible, but inertia (inertial force) would increase, therebyreducing the controllability of the automatic transmission and speedchange shocks would become more likely to occur.

In order to engage or disengage the reduced speed rotation output to theplanetary gear unit from the speed reduction planetary gearing, a clutchor brake must be provided. When a clutch is provided, this clutch andthe above-mentioned two clutches, in other words three clutches, arenecessary. In general, a clutch has a drum-shaped member (clutch drum)that transmits the input rotation to the friction plates, and therefore,for example with a problem such as relative rotation, supply of oilpressure to the oil compartment of the hydraulic servo of the clutchmust come from the mid-section of the automatic transmission.

However, if the required three clutches are located on one axial side ofthe planetary gear unit, oil lines for supplying oil pressure to threehydraulic servos are provided in triplicate in the mid-section of theautomatic transmission, and the configuration of the oil lines becomescomplicated.

SUMMARY OF THE INVENTION

Accordingly, the object of the present invention is to provide anautomatic transmission wherein a reduced speed rotation output means islocated on one axial side of the planetary gear unit, and a first clutchand a second clutch are located on the other axial side of the planetarygear unit, and hence to solve the problems mentioned above.

In one aspect, the present invention is an automatic transmissioncomprising: an input shaft that rotates based on output of a drivesource; a planetary gear unit comprised of first, second, third, andfourth rotary components; reduced speed rotation output means forreducing the speed of rotation of the input shaft and for output of areduced speed rotation to the first rotary component; a first clutch forselectively engaging/disengaging the input shaft to/from the secondrotary component; a second clutch for selectively engaging/disengagingthe input shaft to/from the third rotary component; and an output unitfor outputting the rotation of the fourth rotary component to the drivewheels; wherein at least five forward speeds and one reverse speed areachieved, and wherein a directly coupled state can be achieved whereinthe rotation of the input shaft is output without change in speed byengagement of the first clutch and the second clutch while in fifthspeed forward or higher; and wherein the reduced speed rotation outputmeans is located on one axial side of the planetary gear unit, and anoutput member is located between the planetary gear unit and the reducedspeed rotation output means; and wherein the first clutch and the secondclutch are located on the other axial side of the planetary gear unit.

Accordingly, while providing an automatic transmission which is directlycoupled in fifth speed forward, which provides at least five forwardspeeds and one reverse speed, the reduced speed rotation output meansand the planetary gear unit can be located closer together, as comparedto the case wherein a clutch is located between the reduced speedrotation output means and the planetary gear unit for example, and thetransmitting element(s) for transmitting the reduced speed rotation canbe made relatively short. Therefore, the automatic transmission can bemade compact and lightweight, and further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be improved, and the occurrence of speed change shock can bereduced. Further, in the case that, for example, the reduced speedrotation output means has a clutch, three clutches are required, butcompared to the case wherein three clutches are located on one side ofthe planetary gear unit, the construction of the oil lines which supplyoil pressure to the hydraulic servos for these clutches is simplified,the manufacturing process is simplified and the manufacturing costs arereduced.

Further, because the output unit is located axially intermediate theplanetary gear unit and the reduced speed rotation output means, theoutput unit can be located in approximately the axial center of theautomatic transmission. For example, when the automatic transmission ismounted on a vehicle, enlargement toward the rear (when the input sidefor receiving power from the drive source is the front) becomesunnecessary because the output unit is mounted to mate with the drivewheel transmission mechanism. Because of this, particularly in the caseof a FF vehicle, interference with the front wheels is reduced, and themountability on a vehicle is improved. For example, the steering angleis greatly improved.

The reduced speed rotation output means preferably includes a speedreducing planetary gear unit that has a reduced speed rotary componentthat rotates at the reduced speed rotation and a third engagingcomponent for controlling the rotation of a component of the speedreducing planetary gear unit. Preferably, the third engaging componentengages in the first speed forward.

The speed reducing planetary gear unit preferably includes an inputrotary component that continuously receives as input the rotation of theinput shaft, a reduced speed rotary component that rotates at a reducedspeed and a third component that is fixed for speed reduction, wherebythe reduced speed rotary component rotates at a speed based on therotation of the input rotary component and fixation of third component;and the third engaging component is a third clutch forengaging/disengaging the reduced speed rotary component to/from thefirst rotary component.

In some of the preferred embodiments the third component is anon-rotatable carrier fixed to the transmission case through an endplate and in other preferred embodiments is a rotatable carrier which isfixed against rotation by engagement by a brake.

Accordingly, because the reduced speed rotation output means includes athird clutch, three clutches in total are required, but because thespeed reducing second planetary gear unit is located on one axial sideof the first planetary gear unit, and the first clutch and the secondclutch are located on the other axial side, compared to a design whereinthese three clutches are located on one side of the first planetary gearunit, the construction of an oil line to provide oil to the hydraulicservos for these clutches is simplified, the manufacturing process issimplified and the manufacturing costs are reduced.

The third clutch is preferably located on the side of the firstplanetary gear unit axially opposite the speed reducing (second)planetary gear unit; and the third clutch comprises a third hydraulicservo that engages friction members, a drum unit that is constructedintegrally with the third hydraulic servo and opens toward the speedreducing planetary gear unit, and a hub unit; wherein the thirdhydraulic servo is disposed on a boss extending from the case, and oilis supplied to the hydraulic servo from an oil path in the boss.

In another embodiment the speed reducing second planetary gear unitincludes the input rotary component that receives as input the rotationof the input shaft, a third component fixed against rotation, and areduced speed rotary component that rotates at a reduced speed based onthe rotation of the input rotary component and the fixed carrier;wherein the third engaging component is a third clutch thatengages/disengages the input shaft to/from the input rotary component.

Accordingly, in the latter-described embodiment also, because the speedreducing second planetary unit comprises the third clutch, threeclutches are required, but here too the speed reducing second planetarygear unit is located on the side of the first planetary gear unitopposite the first and second clutches.

Further, because engagement of the third clutch connects the input shaftand the input rotary component, the load on the third clutch can bereduced, and the third clutch can be made more compact, as compared withthe case wherein the third clutch connects the input rotary componentand the first rotary component.

The third clutch comprises a hydraulic servo that engages frictionmembers, a drum unit that is constructed integrally with the hydraulicservo, and a hub unit; and wherein the hub unit is linked with the inputrotary component; and wherein the drum unit is linked to the inputshaft, and is positioned so as to open toward the speed reducing secondplanetary gear unit.

Also, the input rotary component which rotates at a high speed in sixthspeed forward can be linked to the hub unit which has a smaller diameterthan the drum unit and, as compared to the case wherein it is linked tothe drum unit, the centrifugal force is reduced, and controllability ofoperation of the third clutch is improved.

The hydraulic servo of the third clutch may be mounted on the inputshaft, whereby it can receive supply of oil via an oil path within theinput shaft. Alternatively, the hydraulic servo of the third clutch maybe mounted on a boss extending from the case, whereby it can receivesupply of oil via an oil path within the boss.

In another embodiment the speed reducing second planetary gear unitcomprises an input rotary component that receives as input the rotationof the input shaft, a reduced speed rotary component and a rotatablethird component, whereby said reduced speed rotary component rotates ata reduced speed based on the rotation of the input rotary component withthe rotatable third component fixed against rotation, and wherein thethird engaging component is a third brake for fixing the rotatable thirdcomponent against rotation.

The third brake may be located on the axial side of the first planetarygear unit opposite the speed reducing planetary gear unit; and thehydraulic servo of the third brake may be formed in the end wall of thecase.

In another preferred embodiment the first clutch engages in first speedreverse. Accordingly, when in reverse, with the first clutch engaged,one unit (particularly the transmitting member) rotates in reverse atreduced speed from the reduced speed rotation output means, while theunit connecting the first clutch and the second rotary component rotatesat the speed of the input shaft, in some cases the difference betweenthese speeds may be large. However, because the first clutch is locatedon the side of the first planetary gear unit opposite the reduced speedrotation output means, the unit with reverse rotation (particularly thetransmitting member) and the unit rotating at the speed of the inputshaft can be spaced apart, and compared with the case wherein forexample those units are in contact in a multi-axial construction, adecrease in efficiency of the automatic transmission resulting from therelative rotation between these units can be prevented.

In another preferred arrangement, the first clutch adjoins the firstplanetary gear unit and comprises friction members, a hydraulic servothat causes the friction members to engage, and a drum unit and a hubunit that are constructed integral with the hydraulic servo. In thispreferred configuration the drum unit is linked with the input shaft,and the hub unit is linked with the second rotary component. Further,the second clutch is on the side of the speed reducing second planetarygear unit axially opposite the first clutch. Here, the second clutchalso comprises friction members and a hydraulic servo that causes thefriction members to engage, and a drum unit and a hub unit that areintegral with this hydraulic servo. In such an embodiment the drum unitof the second clutch is linked with the input shaft, and the hub unit islinked with the third rotary component, radially inward of the firstclutch.

The present invention may further include a first brake capable offixing the second rotary component against rotation, and a second brakefor braking the third rotary component, with the first brake locatedradially outward of the first clutch and the second brake locatedradially outward of the first planetary gear unit.

The first brake includes friction members and a hydraulic servo thatcauses engagement of the friction members. The hydraulic servo of thefirst brake is preferably located radially outward of the hydraulicservo of the first clutch, at a position at least partially axiallyoverlapping same. The friction members of the first brake include platessplined to the case and, intermeshed therewith, friction members splinedto the hub unit of the first clutch.

Likewise, the second brake includes friction members and a hydraulicservo that controls engagement/disengagement of the friction members.The hydraulic servo of the second brake is preferably formed in aportion of the case, extending radially inward as a transverse wallwhich rotatably supports the output member, and the friction members ofthe second brake are preferably located radially outward of the firstplanetary gear unit.

A transmitting member links the reduced speed rotary element of thesecond planetary gear unit or the third engaging component and the firstrotary element of the first planetary gear, said transmitting memberincluding an axially extending portion radially inward of the outputunit.

The automatic transmission of the present invention may further includea differential unit for outputting rotation to the drive wheels, and acounter shaft unit for engaging the differential unit, wherein theoutput member is a counter gear meshing with the counter shaft unit.

In a preferred embodiment, the first planetary gear unit is a multipletype planetary gear unit, comprising a first sun gear, a long pinionwhich meshes with the first sun gear, a short pinion which meshes withthe long pinion, a carrier for rotationally supporting the long pinionand the short pinion, a second sun gear meshing with the short pinion,and a ring gear meshing with the long pinion. In this preferredembodiment, the first rotary component is the second sun gear whichreceives the reduced speed rotation of the reduced speed rotation outputmeans, the second rotary component is the first sun gear which isrotatably driven by the input shaft with the first clutch engaged, andwhich is fixed against rotation by engagement of the first brake, thethird rotary is a carrier which receives input of rotation from theinput shaft upon engagement of the second clutch, and which is fixedagainst rotation by engagement of a second brake, and the fourth rotarycomponent is a ring gear linked to the output member.

In the preferred embodiment described immediately above, in first speedforward, reduced speed rotation is input to the first rotary componentfrom the reduced speed rotation output means, and the second brake isengaged. In second speed forward, reduced speed rotation is input to thefirst rotary component from the reduced speed rotation output means, andthe first brake is engaged. In third speed forward, reduced speedrotation is input to the first rotary component from the reduced speedrotation output means, and the first clutch is engaged. In fourth speedforward, reduced speed rotation is input to the first rotary componentfrom the reduced speed rotation output means, and the second clutch isengaged. In fifth speed forward, the first clutch and the second clutchare both engaged and in sixth speed forward, the second clutch and firstbrake are engaged. In first speed reverse, the first clutch and secondbrake are engaged. Thus, in the foregoing preferred embodiment sixforward speeds and one reverse speed are provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view of an automatic transmissionaccording to a first embodiment of the present invention;

FIG. 2 is a table of operations for the automatic transmission of thefirst embodiment;

FIG. 3 is a speed line diagram for the automatic transmission of thefirst embodiment;

FIG. 4 is a schematic cross-sectional view of an automatic transmissionaccording to a second embodiment of the present invention;

FIG. 5 is a schematic cross-sectional view of an automatic transmissionaccording to a third embodiment of the present invention;

FIG. 6 is a table of operations of an automatic transmission accordingto the third embodiment;

FIG. 7 is a speed line diagram for an automatic transmission accordingto the third embodiment;

FIG. 8 is a schematic cross-sectional view of an automatic transmissionaccording to a fourth embodiment of the present invention;

FIG. 9 is a schematic cross-sectional view of an automatic transmissionaccording to a fifth embodiment;

FIG. 10 is a schematic cross-sectional view of an automatic transmissionaccording to a sixth embodiment;

FIG. 11 is a table of operations for an automatic transmission accordingto the sixth embodiment; and

FIG. 12 is a speed line diagram for the automatic transmission of thesixth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described withreference to FIG. 1 through FIG. 3.

The automatic transmission 1 ₁ of the first embodiment of the presentinvention, as illustrated in FIG. 1, is particularly useful for a FF(front engine, front wheel drive) vehicle, and has a case comprising ahousing for a torque converter, not illustrated, and a transmission case3 housing automatic transmission 1 ₁, a counter shaft unit (drive wheeltransmission mechanism), not illustrated, and a differential unit (drivewheel transmission mechanism).

The torque converter is located on an axis centered on an input shaft 2of the automatic transmission device 1 ₁, which is on the same axis asthe output shaft of the engine (not illustrated). Further, the countershaft unit includes a counter shaft (not illustrated) on an axis that isparallel to the input shaft 2, and the above-mentioned differential unithas a lateral axle, not illustrated, on an axis that is parallel to thecounter shaft.

As illustrated in FIG. 1, the automatic transmission 1 ₁ comprises afirst planetary gear unit PU and a second planetary gear unit (speedreducing planetary gear unit) PR on the input shaft 2. The firstplanetary gear unit PU is a multiple-type planetary gear unit, which hasa sun gear S2 (the second rotary component), a carrier CR2 (the thirdrotary component), a ring gear R3 (the fourth rotary component), and asun gear S3 (the first rotary component), as the four rotary components.The carrier CR2 has a long pinion PL that meshes with a sun gear S2 andthe ring gear R3, and a short pinion PS that meshes with the sun gearS3, and the pinions PL and PS are meshed with one another. Further, thesecond planetary gear unit PR is a double pinion planetary gear unitthat has a carrier CR1, wherein a pinion Pb is meshed with a ring gearR1 and a pinion Pa is meshed with a sun gear S1, and the pinions Pa andPb are meshed one to another.

A boss 3 a extends from one edge of the case 3 and forms a sleevesurrounding one end of input shaft 2, and on this boss 3 a is mounted amulti-disc clutch C1 (“reduced speed rotation output means”, the “thirdengaging component”, the “third clutch”) comprising a hydraulic servo11, friction plates 71, and a clutch drum 21.

Hydraulic servo 11 includes a piston unit b for pressing against thefriction plates 71, the clutch drum 21 that has a cylinder unit e, anoil chamber “a” which is formed as a sealed area between the piston unitb and the cylinder unit e with seal rings f and g. A return spring cbiasing the piston unit b towards oil chamber “a”, and a return plate dthat supports one end of return spring c.

Each hydraulic servo is constructed similarly with an oil chamber “a”, apiston unit b, a return spring c, a return plate d, a cylinder unit e,and seal rings f and g, and as such, description thereof will not berepeated.

The oil chamber “a” of hydraulic servo 11 is in communication with anoil line 92 in the boss 3 a, and this oil line 92 is linked to an oilpressure control device not illustrated. Because the hydraulic servo 11is located on the boss 3 a, an oil connection from the oil pressurecontrol unit (not illustrated) to the oil chamber “a” of the hydraulicservo 11 can be formed by one set of seal rings 80 which form a sealbetween the boss 3 a and the clutch drum 21.

The boss 3 a rotatably supports the clutch drum 21. Friction plates 71are splined to the inner circumferential surface of a front section ofthe clutch drum 21 and are engaged/disengaged by hydraulic servo 11 forthe clutch C1. Further, the friction plates 71 of clutch C1 areintermeshed with friction plates splined to the outer surface of thering gear R1 which forms part of the hub unit 31 which is rotatablysupported by the boss 3 a. The carrier CR1 has pinion Pb which mesheswith the ring gear R1, and the pinion Pa which meshes with the sun gearS1 which, in turn, is connected to the input shaft 2. This carrier CR1is secured to the boss 3 a of the case 3 via a side plate, and the sungear S1 is connected to the input shaft 2.

The clutch drum 21 is connected to one end of a transmitting member (thereduced speed rotation output means) 30, that transmits the rotation ofthe ring gear R1 when clutch C1 is engaged, and the other end of thetransmitting member 30 is connected to the sun gear S3 of theabove-mentioned first planetary gear unit PU.

At the other end of the input shaft 2 (left side of diagram) is locateda multi-disc clutch C3 (the second clutch) which includes a hydraulicservo 13, friction plates 73, a clutch drum member 25, and a hub unit26. Further, boss 3 b extends axially from the left (in FIG. 1) end ofthe case 3, forms a sleeve around the input shaft 2 and supports amulti-disc clutch C2 (the first clutch) including a hydraulic servo 12,friction plates 72, a clutch drum 23 and a hub unit 24. Further,radially outward of clutch C2 is located a multi-disc brake B2comprising a hydraulic servo 15 and friction plates 75, such that atleast a part thereof axially overlaps the hydraulic servo 12.

The oil chamber “a” of hydraulic servo 13 connects an oil line 2 bformed on input shaft 2, and this oil line 2 b connects with an oil line93 in the boss 3 b, and line 93, in turn, is linked to an oil pressurecontrol device, not illustrated. In other words, the connection betweenthe oil chamber “a” of hydraulic servo 13 and the oil pressure controldevice, not illustrated, is formed by one set of seal rings 82 thatprovide a seal between the boss 3 b of the case 3 and the input shaft 2.

The oil chamber “a” of the above-mentioned hydraulic servo 12 connectsto an oil line 94 of the boss 3 b, and this oil line 94 connects withthe oil pressure control device, not illustrated. In other words, theconnection between the oil chamber “a” of hydraulic servo 12 and the oilpressure control device, not illustrated, is formed by one set of sealrings 83 that provide a seal between the boss 3 b of the case 3 and anextension of the clutch drum member 23.

The clutch drum 25 of the clutch C3 is connected to the input shaft 2and, splined to a front portion of the inner circumferential surface ofclutch drum 25, are friction plates 73 that are engaged/disengaged byhydraulic servo 13. The inner friction plates 73 of clutch C3 areintermeshed with friction plates splined to a hub unit 26, and this hubunit 26 is connected to the carrier CR2.

The clutch drum 23 of the clutch C2 is connected to the input shaft 2,and the inner circumferential surface of clutch drum 23 has frictionplates 72 splined thereto which are engaged/disengaged by the hydraulicservo 12. The friction plates 72 of clutch C2 are intermeshed withfriction plates splined to a hub unit 24. Friction plates 75 of thebrake B2 are intermeshed with friction plates splined to the outercircumferential surface of hub unit 24 and are engaged/disengaged byhydraulic servo 15 for the brake B2. This hub unit 24 is also connectedto the sun gear S2.

On the radially outer side of the first planetary gear unit PU is amulti-disc brake B1 (second brake) that comprises a hydraulic servo 14,friction plates 74, and a hub unit 28. The hydraulic servo 14 is formedin a member extending radially inward from the case 3 and rotatablysupporting a counter gear 5. Also, a side plate of the carrier CR2 ofthe first planetary gear unit PU is connected to hub unit 28 to whichare splined the friction plates 74 meshing with friction plates of theabove-mentioned brake B1. Further, hub unit 28 is connected to the innerrace of a one-way clutch F1. The sun gear S3 is meshed with the shortpinion PS of this carrier CR2, and the above-mentioned sun gear S2 andring gear R3 are meshed with the long pinion PL of this carrier CR2.Also, a linking member 27 is connected to one end of ring gear R3, andthereby links ring gear R3 to the counter gear (output unit) 5.

As described above, the second planetary gear unit PR and the clutch C1are located at one axial side of the first planetary gear unit PU,whereas the clutch C2 and the clutch C3 are located on the other axialside. Further, the counter gear 5 is located axially between the secondplanetary gear unit PR and the first planetary gear unit PU. Further,the first brake B2 is located radially outward of the clutch C2, and thesecond brake B1 is located radially outward of the first planetary gearunit PU.

Operation of the automatic transmission 1 ₁ will now be described, withreference to FIG. 1, FIG. 2, and FIG. 3. The vertical axes of the speedline diagram illustrated in FIG. 3 show the speed of rotation of eachrotary component, and the horizontal axis indicates the correspondinggear ratio of these rotary components. Further, in the first planetarygear unit PU section of this speed line diagram, the vertical axes atthe right side of FIG. 3 correspond to the sun gear S3, and moving tothe left within the diagram, the vertical axes correspond, successively,to the ring gear R3, the carrier CR2, and the sun gear S2. In the secondplanetary gear unit PR section of this speed line diagram (right sectionin FIG. 3), the vertical axis to the farthest right side of FIG. 3corresponds to the sun gear S1, and, moving to the left within thediagram, the vertical axes correspond to, successively, the ring gear R1and the carrier CR1. Further, the widths between these vertical axes areinversely proportional to the number of teeth of each of the sun gearsS1, S2, S3, and to the number of teeth of each of the ring gears R1, R3.The horizontal dotted line within the diagram represents the rotationtransmitted from the transmitting member 30.

As illustrated in FIG. 1, the rotation of the input shaft 2 is input tothe sun gear S2, by engaging the clutch C2, and the rotation of this sungear S2 can be stopped (braked) by engagement of the brake B2 (“firstbrake”). The rotation of the input shaft 2 is input to the carrier CR2by engaging the clutch C3, and this carrier CR2 can be held againstrotation by engagement of the brake B2, and further, the rotation islimited to one direction by a one-way clutch F3.

The above-mentioned sun gear S1 is connected to and receives input ofrotation from the input shaft 2. The carrier CR1 is fixed to the case 3and, therefore, the ring gear R1 rotates at a reduced speed. Further, byengaging the clutch C1, the reduced speed rotation of this ring gear R1is input to the sun gear S3. The rotation of the ring gear R3 is outputto the counter gear 5, and from the counter gear 5 to the drive wheels,not illustrated, via this counter gear 5, a counter shaft unit notillustrated, and a differential unit.

In first speed forward within D (drive) range, as illustrated in FIG. 2,the clutch C1 and the one-way clutch F1 are engaged. Then, asillustrated in FIG. 3, the reduced speed rotation of the ring gear R1 isinput to the sun gear S3 via the clutch C1 and the transmitting member30. Further, the rotation of the carrier CR2 is limited to one direction(the forward rotation direction) by the one-way clutch F1. The ring gearR3 rotates in the forward rotation for first speed forward, with thereduced speed rotation input to the sun gear S3 and the fixed carrierCR2, and that rotation is output from the counter gear 5.

For downshifting (when coasting), the brake B1 is engaged to fix thecarrier CR2, and the first speed forward is maintained while preventingforward rotation of this carrier CR2. Further, in first speed forward,the one-way clutch F1 prevents the carrier CR2 from rotation in thereverse direction while allowing forward rotation, and therefore,switching from a non-running range to a running range and achieving thefirst speed forward can be accomplished more smoothly by the automaticengaging of the one-way clutch. In this case, because the sun gear S3and the ring gear R1 are rotating at a reduced speed, theabove-mentioned transmitting member 30 transmits a relatively largetorque.

In second speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C1 and the brake B2 are engaged. Then, as illustratedin FIG. 3, the reduced speed rotation of the ring gear R1 is input tothe sun gear S3 via the clutch C1 and the transmitting member 30, andthe rotation of the sun gear S2 is stopped by the brake B2. By doing so,the carrier CR2 rotates at a slightly reduced speed, and from thereduced speed rotation input to the sun gear S3 and this slightlyreduced speed rotation of the carrier CR2, the ring gear R3 is rotatedwith the forward rotation for the second speed forward, and thisrotation is output to the counter gear 5. Because the sun gear S3 andthe ring gear R1 are rotating at a reduced speed, the above-mentionedtransmitting member 30 transmits a relatively large torque.

In third speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C1 and the clutch C2 are engaged. Then, asillustrated in FIG. 3, the reduced speed rotation of the ring gear R1 isinput to the sun gear S3 via the clutch C1 and the transmitting member30, and also the rotation of the input shaft 2 is input to the sun gearS2 by engaging the clutch C2. Further, by the rotation of the inputshaft 2 input to the sun gear S2 and by the decreased speed rotation ofthe sun gear S3, the speed of rotation of carrier CR2 is reduced to aslightly larger extent than the reduction in rotational speed of thissun gear S3. Further, from the input rotation of the sun gear S2 and thereduced speed rotation of the sun gear S3, the ring gear R3 is rotatedwith the forward rotation of third speed forward, and this rotation isoutput from the counter gear 5. In this case also, because the sun gearS3 and the ring gear R1 are rotating at a reduced speed, theabove-mentioned transmitting member 30 transmits a relatively largetorque.

In fourth speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C1 and the clutch C3 are engaged. Then, asillustrated in FIG. 3, the reduced speed rotation of the ring gear R1 isinput to the sun gear S3 via the clutch C1 and the transmitting member30, and also the rotation of the input shaft 2 is input to the carrierCR2 via the clutch C3. Then, by the rotation of input shaft 2 input tothe carrier CR2 and by the reduced speed rotation of the sun gear S3,the ring gear R3 is rotated with the forward rotation of fourth speedforward, and this rotation is output from the counter gear 5. In thiscase also, because the sun gear S3 and the ring gear R1 are rotating ata reduced speed, the transmitting member 30 transmits a relatively largetorque.

In fifth speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C2 and the clutch C3 are engaged. Then, asillustrated in FIG. 3, the rotation of input shaft 2 is input to thecarrier CR2 via the clutch C3, and also the rotation of the input shaft2 is input to the sun gear S2 via the clutch C2. Then, from the rotationof the input shaft 2 input to the sun gear S2, and the rotation of theinput shaft 2 input to the carrier CR2, the ring gear R3 becomesdirectly connected and rotates with the forward rotation of fifth speedforward which is at the same speed as that of the input shaft 2, andthis rotation is output from the counter gear 5.

In sixth speed forward within the D (drive) range, as illustrated inFIG. 2, the clutch C3 and the brake B2 are engaged. Then, as illustratedin FIG. 3, the rotation of the input shaft 2 is input to the carrier CR2via the clutch C3, and rotation of the sun gear S2 is fixed byengagement of the brake B2. Then, from the rotation of the input shaft 2input to the carrier CR2 with the sun gear S2 fixed, the ring gear R3rotates with the overdrive rotation of sixth speed forward, and thisrotation is output from the counter gear 5.

In first speed reverse within R (reverse) range, as illustrated in FIG.2, the clutch C2 and the brake B1 are engaged. Then, as illustrated inFIG. 3, the rotation of the input shaft 2 is input to the sun gear S2 byengaging the clutch C2, and also the rotation of the carrier CR2 isfixed by engagement of the brake B1. Then, from the rotation of theinput shaft 2 input to the sun gear S2 and the fixing of the carrierCR2, the ring gear R3 rotates in the opposite direction, i.e., as firstspeed reverse, and this rotation is output from the counter gear 5.

In the P (parking) range and the N (neutral) range, the clutch C1,clutch C2, and clutch C3 are released, the transmission of rotationbetween the input shaft 2 and the counter gear 5 is disconnected, andthe automatic transmission 1 ₁ as a whole is in an idle state (neutralstate).

As described above, in the automatic transmission 1 ₁ of the presentinvention, the second planetary gear unit PR and the clutch C1 arelocated on one axial side of the first planetary gear unit PU, and theclutches C2 and C3 are located on the other axial side of the firstplanetary gear unit PU. Therefore, an automatic transmission is providedthat will achieve six forward speeds and one reverse speed with directcoupling in fifth speed forward. For example, compared to the casewherein the clutch C2 or clutch C3 is located between the secondplanetary gear unit PR and the first planetary gear unit PU, the secondplanetary gear unit PR and the first planetary gear unit PU can belocated closer together, and the transmitting member 30 which transmitsthe reduced speed rotation can be made relatively short. Therefore, theautomatic transmission can be made more compact and lightweight, andfurther, because the inertia (inertial force) can be reduced, thecontrollability of the automatic transmission can be improved, and theoccurrence of speed change shock can be reduced.

Further, the clutch C1 is located on one axial side of the firstplanetary gear unit PU, and the clutches C2 and C3 are located on theother axial side of the first planetary gear unit PU, and therefore,compared to the case wherein three clutches C1, C2, C3 are located onone axial side of the first planetary gear unit PU, the construction ofan oil line (for example, 2 b, 92, 93, 94) for providing oil pressure tothe hydraulic servos 11, 12, and 13 for these clutches C1, C2, and C3can be easily made, the manufacturing process can be simplified, and thecosts brought down.

Further, because the hydraulic servo 13 is mounted on the input shaft 2,one set of seal rings 82 form a seal between the case 3 and the oil line2 b provided within the input shaft 2, and therefore oil can be suppliedto the oil chamber “a” of the hydraulic servo 13 without providingadditional seal rings between, for example, the input shaft 2 and thehydraulic servo 13. Further, the hydraulic servos 11 and 12 can eachreceive supply of oil directly from the bosses 3 a and 3 b, i.e.,without passing through other units. In other words, oil can be suppliedsimply by providing one set of seal rings 82, 80, and 83 each for thehydraulic servos 11, 12, and 13, sliding resistance from the seal ringscan be minimized, and therefore, the efficiency of the automatictransmission can be improved.

Further, since clutch C2 is engaged in first speed reverse, thetransmitting member 30 rotates in reverse, and while the hub unit 24that connects this clutch C2 and the sun gear S2 has the same rotationalspeed as the input shaft 2, there may be cases wherein the difference ofrotational speeds between transmitting member 30 and the hub unit 24becomes large, but because clutch C2 is located on the side of the firstplanetary gear unit PU opposite the second planetary gear unit PR, thetransmitting member 30 and the hub unit 24 can be located apart from oneanother. Compared to the case wherein, for example, those parts come incontact due to a multi-axial construction, the loss of efficiency of theautomatic transmission caused by the friction produced by the relativerotation between those parts can be prevented.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. For example, when the automatic transmission ismounted on a vehicle, enlargement toward the rear (when the input sidefrom the drive source is the front direction) can be prevented becausethe counter gear 5 is mounted to mate with the drive wheel transmissionmechanism. Because of this, particularly in the case of a FF vehicle,the interference with the front wheels is reduced, and the mountabilityon a vehicle can be improved. The steering angle is greatly improved,for example.

Because the automatic transmission of the present embodiment is directlycoupled in fifth speed forward, in first speed forward or fourth speedforward, the gear ratio can be more precisely set for efficiency, andparticularly when the vehicle is running at a high speed, the engine canbe operated at a lower speed, and this contributes to increased fueleconomy of the vehicle while running at a low to medium speed.

Second Embodiment

The second embodiment, which is a partial modification of the firstembodiment, will be described with reference to FIG. 4. Components ofthe second embodiment which are the same as those of the firstembodiment are denoted by the same reference numerals, and descriptionthereof omitted, except for those components which are modified.

As FIG. 4 illustrates, the automatic transmission 1 ₂ of the secondembodiment has the input side and output side reversed from that of theautomatic transmission 1 ₁ of the first embodiment (see FIG. 1).Further, the operations of first speed forward through the sixth speedforward and the first speed reverse are similar (see FIG. 2 and FIG. 3).

Accordingly, similar to the first embodiment, in the automatictransmission 1 ₂ of the second embodiment, the second planetary gearunit PR and the clutch C1 are located on one axial side of the firstplanetary gear unit PU, and the clutch C2 and the clutch C3 are locatedon the other axial side of the first planetary gear unit PU, andtherefore directly coupled when at fifth speed forward, and can achievesix forward speeds and one reverse speed. In this second embodimentalso, the second planetary gear unit PR and the first planetary gearunit PU can be located closer together, compared to the case wherein,for example, the clutch C2 and the clutch C3 are located between thesecond planetary gear unit PR and the planetary gear unit PU, and thetransmitting member 30 which transmits the reduced speed rotation can bemade relatively short. Therefore, the automatic transmission can be madecompact and lightweight, and further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be improved, and the occurrence of speed change shock can bereduced.

Further, the clutch C1 is located on one axial side of the planetarygear unit PU, and the clutch C2 and the clutch C3 are located on theother axial side of the first planetary gear unit PU, and therefore,compared to the case wherein, for example, the three clutches C1, C2,and C3 are located on one side of the first planetary gear unit PU, theoil line (for example, 2 b, 92, 93, 94) for providing oil to thehydraulic servos 11, 12, and 13 for operating these clutches C1, C2, andC3 can be easily constructed, i.e., the manufacturing process issimplified and the costs reduced.

Further, because the hydraulic servo 13 is provided on the input shaft2, one set of the seal rings 82 form an oil supply connection of oilline 93 in boss 3 b to the oil line 2 b provided within input shaft 2,and therefore oil can be supplied to the oil chamber “a” of thehydraulic servo 13 without providing seal rings between, for example,the input shaft 2 and the hydraulic servo 13. Further, the hydraulicservos 11 and 12 can each receive supply of oil directly from the bossunits 3 a and 3 b provided from the case 3, i.e., without passingthrough other units. In other words, their supply of oil can be securedby providing one set of seal rings 80 and 83. Therefore, oil can besupplied simply by providing one set of the seal rings 82, 80, and 83each for the hydraulic servos 11, 12, and 13, sliding resistance fromthe seal rings can be minimized, and therefore the efficiency of theautomatic transmission can be improved.

Further, with clutch C2 engaged in first speed reverse, there may be alarge difference in rotational speeds between the transmitting member 30which rotates in reverse and the hub unit 24 that connects this clutchC2 and the sun gear S2 and which has the same rotation as the inputshaft 2. However, because this clutch C2 is located on the side of theplanetary gear unit PU opposite the second planetary gear unit PR, thetransmitting member 30 and the hub unit 24 can be located apart from oneanother. Compared to the case wherein, for example, those parts come incontact due to a multi-axial construction, the decreased efficiency ofthe automatic transmission caused by the friction produced by therelative rotation between those parts can be prevented.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. For example, when the automatic transmission ismounted on the vehicle, enlargement towards the rear (when the inputside from the drive source is the front) is not required because thecounter gear 5 is mounted to mate with the drive wheel transmissionmechanism. Because of this, particularly in the case of an FF vehicle,the interference with the front wheels is reduced, the mountability on avehicle is improved, and the steering angle is greatly improved.

Further, the automatic transmission 1 ₂ according to the secondembodiment is directly coupled in fifth speed forward. Therefore, infirst speed forward or fourth speed forward, the gear ratio can be setmore precisely, and particularly when the vehicle is running at a highspeed, the engine can be operated at lower speed, and this contributesto increased fuel economy of the vehicle while running at a low tomedium speed.

Third Embodiment

The third embodiment, which is a partial modification of the firstembodiment will now be described with reference to FIG. 5 through FIG.7. Components of the third embodiment which are the same as those of thefirst embodiment are denoted by the same reference numerals, anddescription thereof omitted, except for components which are partiallymodified.

As FIG. 5 illustrates, the automatic transmission 1 ₃ of the thirdembodiment has a modified second planetary gear unit PR and modifiedclutch C1, and further, a modified oil line for supplying oil pressureto hydraulic servo 1 ₁ of the clutch C1, as compared to the automatictransmission 1, of the first embodiment (see FIG. 1).

Within the automatic transmission 1 ₃, the clutch C1 is located on theside of the second planetary gear unit PR opposite the planetary gearunit PU. The inner circumferential surface of the drum 21 of clutch C1is splined to the friction plates 71 which are intermeshed with frictionplates splined to the hub unit 22. The drum 21 is connected to the inputshaft 2, and the hub unit 22 is connected to the sun gear S1 of thesecond planetary gear unit PR. The side plate of the carrier CR1 of thissecond planetary gear unit PR is fixed to and supported by the case 3.Also, the ring gear R1 is connected to the transmitting member 30, andthis transmitting member 30 is connected to the sun gear S3. In otherwords, the ring gear R1 and the sun gear S3 are constantly connectedwith one another, with no clutch located therebetween, and rotation canbe constantly transmitted.

The oil compartment of this hydraulic servo 11 is linked to an oil line2 a which is formed in the input shaft 2, and this oil line 2 a isconnected to the oil line 91 in the boss 3 a which surrounds the inputshaft 2 in the form of a sleeve, and this oil line 91 is linked to anoil pressure control unit not illustrated. Therefore, simply byproviding one set of the seal rings 81 to form a seal between the inputshaft 2 and the boss 3 a, an oil line is established between the oilpressure control device (not illustrated) and the oil compartment of thehydraulic servo 11.

The operations of the automatic transmission 1 ₃ of the third embodimentwill now be described with reference to FIG. 5, FIG. 6, and FIG. 7.Similar to the above-described first embodiment, the vertical axes ofthe speed line diagram illustrated in FIG. 7 indicate the rotationalspeeds of each rotary component, and the horizontal axis indicates thecorresponding gear ratio of these rotary components. Further, in thefirst planetary gear unit PU section of this speed line diagram, thevertical axis to the farthest right in FIG. 7 corresponds to the sungear S3, and moving to the left within the diagram, the vertical axescorrespond to the ring gear R3, the carrier CR2, and the sun gear S2.Further, in the second planetary gear unit PR section of the speed linediagram, the vertical axis to the farthest right in FIG. 7 correspondsto the sun gear S1, and moving to the left within the diagram, thevertical axes correspond to, in succession, the ring gear R1 and thecarrier CR1. Further, the distances between these vertical axes areinversely proportional to the number of teeth of each of the sun gearsS1, S2, S3, and to the number of teeth of each of the ring gears R1, R3.Also, the horizontal dotted line within the diagram represents therotation transmitted by the transmitting member 30.

As illustrated in FIG. 5, by engaging the clutch C1, the rotation of theinput shaft 2 is input to the sun gear S1. Further, the rotation of theabove-mentioned carrier CR1 is fixed to the case 3, and the ring gear R1is rotated at a decreased speed based on the rotation of the input shaft2 input to sun gear S1. In other words, by engaging the clutch C1, thereduced speed rotation of the ring gear R1 is input to the sun gear S3via the transmitting member 30.

Then, as illustrated in FIG. 6 and FIG. 7, within the second planetarygear unit PR, in first speed forward, second speed forward, third speedforward, and fourth speed forward, the rotation of the input shaft 2 isinput to the sun gear S1 by engaging the clutch C1, reduced speedrotation is output to the ring gear R3 from the fixed carrier CR1, andthe reduced speed rotation is input to the sun gear S3 via thetransmitting member 30. At this time, the ring gear R1 and the sun gearS3 are rotating at a reduced speed, and therefore the transmittingmember 30 transmits a relatively large torque. On the other hand, infifth speed forward, sixth speed forward, and first speed reverse, therotation of the sun gear S3 is input to the ring gear R1 via thetransmitting member 30, and further, because the clutch C1 is released,as illustrated in FIG. 7, the sun gear S1 rotates based on the speed ofthe ring gear R1 and fixing of the carrier CR1.

The operations of the planetary gearing, other than those of theabove-described second planetary gear unit PR, are similar to those ofthe first embodiment, (see FIG. 2 and FIG. 3), and accordingly,description thereof will be omitted.

As described above, in the automatic transmission 1 ₃ of the thirdembodiment, the second planetary gear unit PR and the clutch C1 arelocated on one axial side of the first planetary gear unit PU, and theclutch C2 and the clutch C3 are located on the other axial side of thefirst planetary gear unit PU. Therefore, the automatic transmission ofthe third embodiment will achieve six forward speeds and one reversespeed, with direct coupling at the fifth speed forward. For example,compared to the case wherein the clutch C2 or clutch C3 is locatedbetween the second planetary gear unit PR and the first planetary gearunit PU, in the third embodiment the second planetary gear unit PR andthe first planetary gear unit PU can be located closer together, and thetransmitting member 30 which transmits the reduced speed rotation can bemade relatively short. Therefore, the automatic transmission of thethird embodiment can be made more compact and lightweight, and further,because the inertia (inertial force) can be reduced, the controllabilityof the automatic transmission can be improved, and the occurrence ofspeed change shock can be reduced.

Further, the clutch C1 is on one axial side of the first planetary gearunit PU, and the clutch C2 and the clutch C3 are located on the otheraxial side of the planetary gear unit PU, and therefore, compared to thecase wherein, for example, the three clutches C1, C2, and C3 are locatedon one side of the planetary gear unit PU, the construction of an oilline (for example, 2 a, 2 b, 91, 93, 94) for providing oil pressure tothe hydraulic servos 11, 12, and 13 for these clutches C1, C2, and C3can be made more easily, the manufacturing process can be simplified,and the costs can be reduced.

Further, because the hydraulic servos 11 and 13 are provided on theinput shaft 2, one set of the seal rings 81 and 82 provide a sealbetween the bosses 3 a and 3 b of the case 3 and the oil lines 2 a, and2 b provided within the input shaft 2, and therefore oil can be suppliedto the oil compartments of the hydraulic servos 11 and 13 withoutproviding seal rings between, for example, the input shaft 2 and thehydraulic servos 11 and 13. Further, the hydraulic servo 12 can bedirectly supplied with oil from the boss 3 b, i.e., without passingthrough other units for example. In other words, the supply of oil canbe established by providing one set of the seal rings 83. Therefore, oilcan be supplied simply by providing sets of seal rings 81 and 82, 83 forthe respective hydraulic servos 11, 12, and 13, sliding resistance fromthe seal rings can be minimized, and therefore the efficiency of theautomatic transmission can be improved.

Further, when clutch C2 is engaged in first speed reverse and thetransmitting member 30 rotates in reverse, there may be cases wherein byengaging clutch C2, the hub unit 24 connecting this clutch C2 and thesun gear S2 will rotate at the speed of the input shaft 2, and somecases may occur wherein the difference in rotational speeds between thetransmitting member 30 and the hub unit 24 may be large. However,because this clutch C2 is located on the side of the first planetarygear unit PU opposite the second planetary gear unit PR, that is to saythe transmitting member 30 and the hub unit 24 can be spaced apart,compared with a construction wherein those units are in contact with amulti-axial construction, the loss of efficiency of the automatictransmission produced by friction resulting from the relative rotationbetween those units can be prevented.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. Thus, when the automatic transmission is mountedon the vehicle, enlargement toward the rear (when the input side fromthe drive source is the front) is not required because the counter gear5 is mounted to mate with the drive wheel transmission mechanism.Because of this, particularly in the case of a FF vehicle, interferencewith the front wheels is reduced, the mountability on a vehicle isimproved, and the steering angle is greatly improved.

Further, the automatic transmission 1 ₃ of the third embodiment isdirectly coupled in fifth speed forward. Therefore, in first speedforward and fourth speed forward, the gear ratio can be more preciselyset for best efficiency, and particularly when the vehicle is running ata high speed, the engine speed can be reduced, and this contributes toincreased fuel economy of the vehicle while running at a low to mediumspeed.

Japanese Unexamined Patent Application Publication No. 8-68456 disclosesa transmission wherein a clutch is located in the power path of reducedspeed rotation transfer from the speed reducing planetary gear unit tothe rotary component of the first planetary gear unit, and because thispower path transmits this reduced speed rotation with high torque, theclutch or members within the power path that transmits the high torquemust be constructed so as to withstand this high torque. Further, themember(s) constituting the power path line for transmitting this reducedspeed rotation rotate at a high speed, for example, when in sixth speedforward, and therefore, as in the above-mentioned Publication, in theevent that the transmission member(s) links the drum of the clutch tothe input rotary component of the first planetary gear unit,controllability is lost when engaging and releasing this clutch becausethe drum unit changes shape because of the centrifugal force generatedat high speed. Therefore, it is an object of the present invention toprovide an automatic transmission wherein the controllability of theclutch utilized as a reduced speed rotation output means, is not losteven at high speed rotation of the rotary component of the firstplanetary gear unit.

In the automatic transmission 1 ₃ of the third embodiment, the clutch C1connects/disconnects the input shaft 2 and the sun gear S1 and,therefore, compared for example, with a transmission wherein the clutchC1 connects/disconnects the ring gear R1 and the sun gear S3, the loadon the clutch C1 is less, loss of controllability of the clutch C1 isprevented, and further, the clutch C1 can be made more compact.

Further, the drum 21 of the clutch C1 is linked to the input shaft 2,and the hub unit 22 is linked to the sun gear S1 of the second planetarygear unit PR, and therefore, the hub unit 22 which has a smallerdiameter than the clutch drum 21 can be linked, for example, with thesun gear S1 that rotates at a high speed when in sixth speed forward.Thus, compared to the case wherein the sun gear S1 is linked to theclutch drum, in this third embodiment the centrifugal force can bereduced, and reduction of controllability of the clutch C1 when engagingand releasing can be prevented.

Fourth Embodiment

The fourth embodiment, which is a partial modification of the thirdembodiment will be described with reference to FIG. 8. Components of thefourth embodiment which are the same as those of the third embodimentare denoted by the same reference numerals, and description thereofomitted, except for the modified components.

As FIG. 8 illustrates, the automatic transmission 1 ₄ of the fourthembodiment has a modified second planetary gear unit PR and clutch C1,i.e., modification of the automatic transmission of the third embodiment(see FIG. 5).

With the automatic transmission 1 ₄, the clutch C1 is disposed axiallybetween the second planetary gear unit PR and the first planetary gearunit PU, specifically between the second planetary gear unit PR and thecounter gear 5. The drum 21 is connected to one end of the input shaft 2(at the upper right side in the drawing), and the friction plates 71 ofthe clutch C1, which are engaged under control of the clutch C1hydraulic servo 11, are splined to the inner circumferential surface atthe front end of the drum 21 and are intermeshed with friction platessplined to a hub unit 22, and this hub unit 22 is connected to the sungear S1 of the second planetary gear unit PR.

The carrier CR1 of the second planetary gear unit PR carries a pinion Pbwhich meshes with the above-mentioned ring gear R1, and a pinion Pawhich meshes with the sun gear S1 which is connected to the hub unit 22.The carrier CR1 is fixed to the case 3 through the side plate, and thering gear R1 is connected with the transmitting member 30. The sun gearS3 of the first planetary gear unit PU is connected to the other end ofthe transmitting member 30.

Also, the oil chamber “a” of the hydraulic servo 11 of the clutch C1communicates with the oil path 2 a of the input shaft 2, and the oilpath 2 a communicates with an oil pressure control device through theoil path 91 of the boss 3 a. In other words, because the hydraulic servo11 is mounted on the input shaft 2, an oil path from the oil pressurecontrol unit to the oil chamber “a” of the hydraulic servo 11 isconstructed by one set of seal rings 81 which provides a seal betweenthis boss 3 a and the input shaft 2.

The operations of the automatic transmission 1 ₄ of this fourthembodiment are the same as those of the third embodiment (see FIG. 6 andFIG. 7), and accordingly, description thereof will be omitted.

As described above, in the automatic transmission 14 of the fourthembodiment, the second planetary gear unit PR and the clutch C1 arelocated on one axial side of the first planetary gear unit PU, and theclutch C2 and the clutch C3 are located on the other axial side of thefirst planetary gear unit PU. The automatic transmission of the fourthembodiment provides six forward speeds and one reverse speed, withdirect coupling in fifth speed forward. For example, compared to atransmission wherein the clutch C2 or clutch C3 is located between thesecond planetary gear unit PR and the first planetary gear unit PU, inthis fourth embodiment the second planetary gear unit PR and the firstplanetary gear unit PU can be located closer together, and thetransmitting member 30 which transmits the reduced speed rotation can bemade relatively short. Therefore, the automatic transmission can be mademore compact and lightweight, and further, because the inertia (inertialforce) can be reduced, the controllability of the automatic transmissioncan be improved, and the occurrence of speed change shock can bereduced.

Further, the clutch C1 is located on one axial side of the planetarygear unit PU, and the clutch C2 and the clutch C3 are located on theother axial side of the planetary gear unit PU. Therefore, compared to atransmission wherein, for example, the three clutches C1, C2, and C3 arelocated on one axial side of the planetary gear unit PU, theconstruction of an oil line (for example, 2 a, 2 b, 91, 93, 94) toprovide oil to the hydraulic servos 11, 12, and 13 which operate,respectively, clutches C1, C2, and C3 can be easily made, themanufacturing process can be simplified and the costs reduced.

Further, because the hydraulic servos 11 and 13 are on the input shaft2, one set of the seal rings 81 and 82 provides a seal between the case3 and oil lines 2 a, and 2 b provided within the input shaft 2, andtherefore oil can be supplied to the oil compartments of the hydraulicservos 11 and 13 without providing seal rings between, for example, theinput shaft 2 and the hydraulic servos 11 and 13. Further, the hydraulicservo 12 can receive supply of oil directly from the boss 3 b withoutpassing through other units. In other words, oil supply paths areestablished by providing one set of seal rings 81 and 82, 83 each forthe hydraulic servos 11, 12, and 13, sliding resistance from the sealrings can be minimized, and therefore the efficiency of the automatictransmission can be improved.

Further, when the clutch C2 is engaged in first speed reverse, thetransmitting member 30 rotates in reverse, the hub unit 24 that connectsthis clutch C2 and the sun gear S2 has the same rotation as the inputshaft 2, and there may be a large difference in rotation speeds of thetransmitting member 30 and the hub unit 24. However, because this clutchC2 is located on the side of the planetary gear unit PU opposite thesecond planetary gear unit PR, the transmitting member 30 and the hubunit 24 can be spaced apart from one another. Compared to the casewherein, for example, those parts come in contact due to a multi-axialconstruction, the decrease in efficiency of the automatic transmissioncaused by the friction produced by the relative rotation between thoseparts can be prevented.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the center of theautomatic transmission. When the automatic transmission is mounted onthe vehicle, enlargement toward the rear (when the input side from thedrive source is the front) is unnecessary because the counter gear 5 ismounted to mate with the drive wheel transmission mechanism. Because ofthis, particularly in the case of a FF vehicle, interference with thefront wheels is reduced, mountability on a vehicle is improved, and thesteering angle is greatly improved.

Further, the automatic transmission 14 in the fourth embodiment is alsodirectly coupled at fifth speed forward. Therefore, in first speedforward or fourth speed forward, the gear ratio can be more preciselyset for maximum efficiency, and particularly when the vehicle is runningat a high speed, the engine speed can be reduced, and this contributesto increased fuel economy of the vehicle while running at a low tomedium speed.

In the automatic transmission 14 according to the fourth embodiment, theclutch C1 selectively connects/disconnects the input shaft 2 and the sungear S1. Therefore, compared with, for example, a transmission whereinthe clutch C1 connects the ring gear R1 and the sun gear S3, the load onthe clutch C1 can be reduced, reduction in control of the clutch C1 isprevented, and further, the clutch C1 can be made more compact.

Further, the drum 21 of the clutch C1 is linked to the input shaft 2,and the hub unit 22 is linked to the sun gear S1 of the second planetarygear unit PR, and therefore, the hub unit 22 which has a smallerdiameter than the drum 21 can be linked for example with the sun gear S1that rotates at a high speed when in sixth speed forward and, comparedto the case wherein the sun gear S1 is linked to the drum, thecentrifugal force can be reduced, and reduction of controllability ofthe clutch C1 can be prevented.

Fifth Embodiment

The fifth embodiment, which is a partial modification of the thirdembodiment will now be described with reference to FIG. 9. Components ofthe fifth embodiment which are the same as those of the third embodimentare denoted by the same reference numerals, and description thereofomitted, except for the modified components.

As FIG. 9 illustrates, the automatic transmission 1 ₅ of the fifthembodiment has clutch C1 mounted on the boss 3 a, rather than on theinput shaft 2, and in this respect differs from the automatictransmission 1 ₃ of the third embodiment (see FIG. 5).

In the automatic transmission 1 ₅ of the fifth embodiment, the clutch C1is disposed on the side of the second planetary gear unit PR oppositethe first planetary gear unit PU (to the right in the drawing). The drum21 is rotatably supported on the boss 3 a extending from the case 3, andthe inner circumferential surface at the front end of the drum 21 of theclutch C1 is connected to the input shaft 2. The friction plates 71 aresplined to the inner circumferential surface, at the front end, of thedrum 21, and are intermeshed with friction plates splined to the hubunit 22 connected to the second sun gear S1 of the second planetary gearunit PR.

The carrier CR1 of the second planetary gear unit PR has pinion Pb whichmeshes with the ring gear R1, and pinion Pa which meshes with the sungear S1 connected to the hub unit 22. The carrier CR1 is fixed to thecase 3 through a side plate, and the ring gear R1 is connected to oneend of the transmitting member 30. The sun gear S3 of the firstplanetary gear unit PU is connected to the other end of the transmittingmember 30.

The oil chamber “a” of the hydraulic servo 11 of the clutch C1communicates with the oil path 91 in the boss 3 a, and the oil path 91communicates with an unshown oil pressure control device. In otherwords, because the hydraulic servo 11 is mounted on the boss 3 a, an oilsupply path from the oil pressure control unit to the oil chamber “a” ofthe hydraulic servo 11 is constructed with one set of seal rings 81which provide a seal between the boss 3 a and the hydraulic servo 11.

The operations of the automatic transmission 1 ₅ of the fifth embodimentare the same as those of the third embodiment (see FIG. 6 and FIG. 7),and accordingly, description thereof will be omitted.

As described above, in the automatic transmission 1 ₅ of the fifthembodiment, the second planetary gear unit PR and the clutch C1 arelocated on one axial side of the first planetary gear unit PU, and theclutch C2 and the clutch C3 are located on the other axial side of thefirst planetary gear unit PU. The automatic transmission of the fifthembodiment provides six forward speeds and one reverse speed, withdirect coupling in fifth speed forward. In this fifth embodiment also,compared to the case wherein the clutch C2 or clutch C3 is locatedbetween the second planetary gear unit PR and the first planetary gearunit PU, the second planetary gear unit PR and the first planetary gearunit PU can be located closer together, and the transmitting member 30for transmitting the reduced speed rotation can be made relativelyshorter. Therefore, the automatic transmission can be made more compactand lightweight, and further, because the inertia (inertial force) canbe reduced, the controllability of the automatic transmission can beimproved, and the occurrence of speed change shock can be reduced.

Because the clutch C1 is located on one axial side of the firstplanetary gear unit PU, and the clutch C2 and the clutch C3 are locatedon the other axial side of the first planetary gear unit PU, comparedwith the case wherein the three clutches C1, C2, and C3 are located onone axial side of the first planetary gear unit PU, the construction ofan oil supply path (for example, 2 a, 2 b, 91, 93, 94) for providing oilto the hydraulic servos 11, 12, and 13 can be made more easily, themanufacturing process can be simplified and the costs brought down.

Further, because the hydraulic servos 11 and 13 are mounted on the inputshaft 2, the sets of seal rings 81 and 82 seal the bosses 3 a and 3 brespectively to the oil lines 2 a, and 2 b provided within the inputshaft 2, and therefore oil can be supplied to the respective oilcompartments of the hydraulic servos 11 and 13 without providing sealrings between, for example, the input shaft 2 and the hydraulic servos11 and 13. Further, the hydraulic servo 12 can be supplied oil from theboss unit 3 b extending from the case 3, without that supply passingthrough other units or, in other words, can be established by providingone set of the seal rings 83. Therefore, an oil path can be establishedsimply by providing one set of the seal rings 81 and 82, 83 for each ofthe hydraulic servos 11, 12, and 13, sliding resistance from the sealrings can be minimized, and therefore the efficiency of the automatictransmission can be improved.

Further, when clutch C2 is engaged in first speed reverse, thetransmitting member 30 rotates with reverse rotation, and while the hubunit 24 that connects this clutch C2 and the sun gear S2 has the samerotation as the input shaft 2 due to engagement of clutch C2, thedifference between rotational speeds of the transmitting member 30 andthe hub unit 24 may be large. However, because this clutch C2 is locatedon the side of the planetary gear unit PU opposite the second planetarygear unit PR, the transmitting member 30 and the hub unit 24 can bespaced apart from one another. Compared to the case wherein, forexample, those parts come in contact due to a multi-axial construction,the decreased efficiency of the automatic transmission caused by thefriction produced by the relative rotation between those parts can beprevented.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit PU and the second planetary gear unit PR, thecounter gear 5 can be positioned in approximately the axial center ofthe automatic transmission. In this manner, enlargement of thetransmission towards the rear (when the input side facing the drivesource is the front) is not necessary because the counter gear 5 ismounted to mate with the drive wheel transmission mechanism. Because ofthis, particularly in the case of a FF vehicle, the interference withthe front wheels is reduced, the mountability on a vehicle is improved,and the steering angle is greatly improved, for example.

Further, because the automatic transmission 1 ₅ according to the fifthembodiment is directly coupled in fifth speed forward in first speedforward or fourth speed forward, the gear ratio can be more preciselyset for efficiency, and particularly when the vehicle is running at ahigh speed, the engine can be operated more efficiently, and thiscontributes to increased fuel economy of the vehicle while running at alow to medium speed.

Further, in the automatic transmission 1 ₅ of the fifth embodiment, theclutch C1 engages/disengages the input shaft 2 and the sun gear S1 and,therefore, compared with, for example, the case wherein the clutch C1engages/disengages the ring gear R1 and the sun gear S3, the load on theclutch C1 is reduced, controllability of the clutch C1 is retained, andfurther, the clutch C1 can be made more compact.

Further, the clutch C1 is mounted on the boss 3 a wherein the oil path91 from the oil pressure control device is formed, and accordingly, theautomatic transmission 15 can be can be made more axially compact ascompared with the case wherein the clutch C1 is mounted on the inputshaft 2, for example (see FIG. 5).

Further, the drum 21 of the clutch C1 is linked to the input shaft 2,and the hub unit 22 is linked to the sun gear S1 of the second planetarygear unit PR and, therefore, the hub unit 22 which has a smallerdiameter than the drum 21 can be linked for example, with the sun gearS1 that rotates at a high speed in sixth speed forward, and compared tothe case wherein the sun gear S1 is linked to the drum-shaped member,the centrifugal force can be reduced, and controllability of the clutchC1 when engaging and releasing can be retained.

Sixth Embodiment

Next, the sixth embodiment, which is a partial modification of the firstembodiment, will be described with reference to FIG. 10 through FIG. 12.Components of the sixth embodiment which are the same as those of thefirst embodiment are denoted by the same reference numerals, anddescription thereof omitted, except where modified.

As FIG. 10 illustrates, the automatic transmission 1 ₆ of the sixthembodiment includes a brake B3 (the “reduced speed rotation outputmeans”, the “third engaging component”, the “third brake”) in place ofthe clutch C1, and the carrier CR1 of the second planetary gear unit PRis capable of being fixed by the brake B3, in which respects it differsfrom automatic transmission 1 ₁ of the automatic transmission of thefirst embodiment (see FIG. 1).

The brake B3 is located on the side of the second planetary gear unit PUopposite the first planetary gear unit PU (right side of the diagram).This brake B3 comprises a hydraulic servo 16, friction plates 76, and ahub unit 33.

The hub unit 33 of brake B3 is connected to one side plate of thecarrier CR1, and carrier CR1 is rotatably supported by the input shaft 2or the boss 3 a. Further, the sun gear S1 is connected to the inputshaft 2. Also, ring gear R1 is connected to the sun gear S3 viatransmitting member 30.

Operations of the automatic transmission 1 ₆ will now be described withreference to FIG. 11 and FIG. 12. As described in connection with thefirst embodiment, the vertical lines in the speed line diagram of FIG.12 indicate the speeds of various rotary components, and the horizontalaxis shows the corresponding gear ratios of these components. In thefirst planetary gear unit PU section of this speed line diagram, thevertical axis to the farthest right side in FIG. 12 corresponds to thesun gear S3 and, moving to the left within the diagram, the verticallines correspond to the ring gear R3, the carrier CR2, and the sun gearS2. Further, in the second planetary gear unit PR section of this speedline diagram, the vertical axis to the farthest right side of FIG. 12corresponds to the sun gear S1 and, moving to the left within thediagram, the vertical lines correspond to the ring gear R1 and thecarrier CR1. Further, the distances between these vertical lines areinversely proportional to the number of teeth of each of the sun gearsS1, S2, S3, and to the number of teeth of each of the ring gears R1, R3.Also, the dotted horizontal line within the diagram represents therotation transmitted by the transmitting member 30.

As illustrated in FIG. 10, the carrier CR1 is fixed to the case 3 byengagement of the brake B3. Further, the rotation of the input shaft 2is input to the sun gear S1, and the ring gear R1 rotates a lower speedthat the speed of rotation of the input shaft 2 that is input to the sungear S1, with carrier CR1 being fixed. In other words, the reduced speedrotation of the ring gear R1 is input to the sun gear S3 via thetransmitting member 30, by engaging the brake B3.

As FIG. 11 and FIG. 12 illustrate, regarding the second planetary gearunit PR, in first speed forward, second speed forward, third speedforward, and fourth speed forward, the rotation of the input shaft 2 isinput to the sun gear S1 by engaging the brake B3, the carrier CR1 isfixed, and the reduced speed rotation is output to the ring gear R3 bythe rotation of the sun gear S1 which receives the rotation of the inputshaft 2, and the reduced speed rotation is input to the sun gear S3 viathe transmitting member 30. In this case, the ring gear R1 and the sungear S3 are rotating at reduced speed, and therefore the transmittingmember 30 transmits a relatively large torque. On the other hand, infifth speed forward, sixth speed forward, and first speed reverse, therotation of the sun gear S3 is input to the ring gear R1 via thetransmitting member 30, and further, because the brake B3 is released,as FIG. 12 illustrates, the carrier CR1 rotates based on the speed ofring gear R1 and the sun gear S1.

The operations of the second planetary gear unit of the sixthembodiment, other than those mentioned above, are similar to those ofthe above-described first embodiment, and accordingly, descriptionthereof will be omitted.

As described above, in the automatic transmission 1 ₆ of the sixthembodiment, the second planetary gear unit PR and the brake B3 arelocated on one axial side of the first planetary gear unit PU, and theclutch C2 and the clutch C3 are located on the other axial side of thefirst planetary gear unit PU. Therefore, the automatic transmission willachieve six forward speeds and one reverse speed, with direct couplingin fifth speed forward. Compared, for example, with the case wherein theclutch C2 or clutch C3 is located between the second planetary gear unitPR and the first planetary gear unit PU, the second planetary gear unitPR and the first planetary gear unit PU can be located closer together,and the transmitting member 30 can be made relatively shorter.Therefore, the automatic transmission can be made more compact andlightweight, and further, because the inertia (inertial force) can bereduced, the controllability of the automatic transmission can beimproved, and the occurrence of speed change shock can be reduced.

Further, because the hydraulic servo 13 is mounted on the input shaft 2,one set of the seal rings 82 form a seal between the boss 3 b and oillines 2 b provided within the input shaft 2, and therefore oil can besupplied to the oil compartment of the hydraulic servo 13 withoutproviding seal rings between, for example, the input shaft 2 and thehydraulic servo 13. Further, the hydraulic servo 12 can receive oildirectly from the boss 3 b, i.e., without passing through other units.In other words, supply of oil is secured by providing one set of sealrings 83. Therefore, oil can be supplied simply by providing one set ofseal rings 82 and 83 for each of the hydraulic servos 12 and 13, slidingresistance from the seal rings can be minimized, and therefore theefficiency of the automatic transmission can be improved.

Further, when the clutch C2 engages in first speed reverse, thetransmitting member 30 rotates in reverse, and the hub unit 24, thatconnects this clutch C2 and the sun gear S2, has the same rotationalspeed as the input shaft 2, and the difference in rotational speedbetween the transmitting member 30 and the hub unit 24 may be large.However, because this clutch C2 is located on the side of the firstplanetary gear unit PU opposite the second planetary gear unit PR, thetransmitting member 30 and the hub unit 24 can be spaced apart from oneanother. Compared to the case wherein, for example, those parts come incontact in a multi-axial construction, loss in efficiency of theautomatic transmission caused by the friction produced by the relativerotation between those parts can be prevented.

Further, because the counter gear 5 is located axially between the firstplanetary gear unit Pu and the second planetary gear unit PR, thecounter gear 5 can be located in approximately the axial center of theautomatic transmission. As in the previous embodiments, when theautomatic transmission is mounted on the vehicle, enlargement towardsthe rear (when the input side facing the drive source is the “front”) isnot necessary because the counter gear 5 is mounted to mate with thedrive wheel transmission mechanism. Because of this, particularly in thecase of a FF vehicle, interference with the front wheels is reduced,mountability on a vehicle is improved, and the steering angle can begreatly improved, for example.

Further, because output of the reduced speed rotation to the firstplanetary gear unit PU from the second planetary gear unit PR iscontrolled by engagement and disengagement of the brake B3, the numberof components (for example clutch drums and so forth) can be reduced ascompared to the case wherein, for example, a clutch C1 is provided.Further, because the brake B3 can receive oil directly from the case 3,construction of an oil line can be simplified as compared to the casewherein, for example, a clutch C1 is provided.

Further, because the automatic transmission 1 ₆ of the sixth embodimentis directly coupled at fifth speed forward, in first speed forward orfourth speed forward, the gear ratio can be better set for efficiency,and particularly when the vehicle is running at a high speed, the enginecan be run with better efficiency, and this contributes to increasedfuel economy of the vehicle while running at a low to medium speed.

In the automatic transmission 1 ₆ of the sixth embodiment, the carrierCR1 is fixed by the brake B3, and therefore, compared to the casewherein a clutch is used to connect/disconnect ring gear R1 and the sungear S3, the load on the brake B3 can be reduced, this brake B3 can bemade more compact, and the automatic transmission can also be made morecompact.

While the first through sixth embodiments relating to the presentinvention have been described above as being applicable to an automatictransmission having a torque converter, they are not so limited, and anymotion starting device may be used that transmits torque (rotation) atstart of movement. Further, while described as mounted on a vehicle withan engine as a drive source, the invention is not so limited, and anydrive source may be used as a matter of course, and the transmission ofthe present invention may be mounted on a hybrid vehicle. Further, whilethe above-described automatic transmission embodiments are favorablyused in a FF vehicle, again the present invention is not so limited, andcan be used in a FR vehicle, a four-wheel drive vehicle, or vehicleswith other types of drive systems.

Further, while the speed reducing planetary gear unit according to theabove first through sixth embodiments has been described as reducingrotational speed of the ring gear by fixing the carrier while inputtingthe rotation of the input shaft into the sun gear, the invention is notso limited, and may reduce rotational speed of the ring gear by fixingthe sun gear while inputting the rotation of the input shaft into thecarrier.

As described above, the automatic transmission according to the presentinvention is beneficially mounted on vehicles, such as automobiles,trucks, busses, and so forth, which require reduction in size andreduction in weight and further require reduction of shock in changingspeeds.

1. (canceled)
 2. (canceled)
 3. (canceled)
 4. (canceled)
 5. (canceled) 6.(canceled)
 7. (canceled)
 8. (canceled)
 9. (canceled)
 10. (canceled) 11.(canceled)
 12. (canceled)
 13. (canceled)
 14. (canceled)
 15. (canceled)16. (canceled)
 17. (canceled)
 18. (canceled)
 19. (canceled) 20.(canceled)
 21. (canceled)
 22. An automatic transmission comprising: aninput shaft rotatably driven by a drive source; a first planetary gearunit including first, second, third, and fourth rotary components;reduced speed rotation output means for receiving input rotation fromsaid input shaft, for reducing the speed of the input rotation and foroutputting rotation at the reduced speed to said first rotary component;a first clutch that is engageable to connect said input shaft and saidsecond rotary component; a second clutch that is engageable to connectsaid input shaft and said third rotary component; an output unit foroutputting the rotation of said fourth rotary component; wherein saidautomatic transmission provides at least five forward speeds, onereverse speed, and a directly coupled state wherein the rotation of theinput shaft is output without change in speed by engagement of saidfirst clutch and said second clutch in fifth speed and higher; whereinsaid reduced speed rotation output means is located on one axial side ofsaid first planetary gear unit, and said output unit is located betweensaid first planetary gear unit and said reduced speed rotation outputmeans; and wherein said first clutch and said second clutch are locatedon the axial side of said first planetary gear unit opposite said oneaxial side.
 23. An automatic transmission according to claim 22, whereinsaid reduced speed rotation output means comprises a speed reducingsecond planetary gear unit that has a reduced speed rotary element thatrotates at said reduced speed rotation and a third engaging componentfor controlling rotation of the reduced speed rotary element of saidsecond planetary gear unit.
 24. An automatic transmission according toclaim 23, wherein said third engaging component engages in said firstspeed forward.
 25. An automatic transmission according to claim 23,wherein said second planetary gear unit comprises an input rotaryelement that continuously receives input of the rotation of said inputshaft, an intermediate element, and said reduced speed rotary elementthat can be rotated at a reduced speed based on the rotation of saidinput rotary element and fixation against rotation of said intermediateelement; and wherein said third engaging component is a third clutchthat selectively connects said reduced speed rotary element and saidfirst rotary component.
 26. An automatic transmission according to claim25, wherein said third clutch is located on the axial side of saidsecond planetary gear unit opposite said first planetary gear unit;wherein said third clutch comprises a third hydraulic servo, frictionmembers, a drum unit, that is constructed integrally with said thirdhydraulic servo and opens toward said speed reducing second planetarygear unit, and a hub unit; and wherein the third hydraulic servo isdisposed on a boss extending from the case, and oil is supplied to saidthird hydraulic servo from an oil path in said boss.
 27. An automatictransmission according to claim 23, wherein said second planetary gearunit comprises an input rotary element that receives input of therotation of said input shaft, an intermediate element, and said reducedspeed rotary element that can be rotated at a reduced speed based on therotation of said input rotary element and fixation of the intermediateelement against rotation; and and wherein said third engaging componentis a third clutch that selectively connects said input shaft and saidinput rotary element.
 28. An automatic transmission according to claim27, wherein said third clutch comprises a third hydraulic servo,friction members, a drum unit that is constructed integrally with saidthird hydraulic servo, and a hub unit; wherein said hub unit is linkedwith said input rotary element; and and wherein said drum unit is linkedto said input shaft and is positioned so as to open toward said secondplanetary gear unit.
 29. An automatic transmission according to claim28, wherein said third hydraulic servo is mounted on said input shaft;and wherein oil is supplied to said third hydraulic servo via an oilpath within said input shaft.
 30. An automatic transmission according toclaim 28, wherein said third hydraulic servo is mounted on a bossextending from the case; and oil is supplied to said third hydraulicservo via an oil path provided within said boss.
 31. An automatictransmission according to claim 23, wherein said speed reducing secondplanetary gear unit comprises an input rotary component that receives asinput the rotation of said input shaft, a carrier, and said reducedspeed rotary component that can rotate at a reduced speed based on therotation of the input rotary component and fixation of the intermediateelement against rotation; and wherein said third engaging component is athird brake for fixing the intermediate element against rotation.
 32. Anautomatic transmission according to claim 31, wherein said third brakeis on the axial side of said first planetary gear unit opposite saidsecond planetary gear unit; and wherein the hydraulic servo of saidthird brake is formed in a wall of the case.
 33. An automatictransmission according to claim 22, wherein said first clutch engages insaid first speed reverse.
 34. An automatic transmission according toclaim 33, wherein: said first clutch is located adjoining said firstplanetary gear unit; said first clutch comprises friction members and afirst hydraulic servo that causes said friction members to engage anddisengage, and a drum unit and a first hub unit that are constructedintegral with said first hydraulic servo; said first drum unit is linkedwith said input shaft, and said first hub unit is linked with saidsecond rotary component; said second clutch is located on the axial sideof said second planetary gear unit opposite said first clutch; saidsecond clutch comprises friction members, a second hydraulic servo thatselectively engages said friction members, and a second drum unit and asecond hub unit that are constructed integral with said second hydraulicservo; and said second drum unit is linked with said input shaft, andsaid second hub unit is linked with said third rotary component.
 35. Anautomatic transmission according to claim 34, further comprising: afirst brake for fixing said second rotary component against rotation; asecond brake for fixing said third rotary component against rotation;wherein said first brake is located radially outward of said firstclutch; and wherein said second brake is located radially outward ofsaid first planetary gear unit.
 36. An automatic transmission accordingto claim 35, wherein said first brake comprises friction members and ahydraulic servo; wherein the hydraulic servo of said first brake islocated radially outward of and at least partially axially overlappingsaid first hydraulic clutch; and wherein the friction members of saidfirst brake are splined to the case and to the first hub unit.
 37. Anautomatic transmission according to claim 36, wherein said second brakecomprises friction members and a hydraulic servo; wherein the hydraulicservo of said second brake is formed in a wall of the case extendingradially inward and rotatably supporting said output member; and whereinthe friction members of said second brake are located radially outwardof said first planetary gear unit.
 38. An automatic transmissionaccording to claim 25, wherein a transmitting member links (1) thereduced speed rotary element of said second planetary gear unit or saidthird engaging component and (2) the first rotary component of saidfirst planetary gear unit, said transmitting member including an axiallyextending portion radially inward of said output unit.
 39. An automatictransmission according to claim 22, further comprising a differentialunit for outputting rotation to drive wheels, and a counter shaft unitfor engaging said differential unit, wherein said output member is acounter gear meshing with said counter shaft unit.
 40. An automatictransmission according to claim 22, wherein said first planetary gearunit is a multiple type planetary gear unit, comprising a first sungear, a long pinion which meshes with said first sun gear, a shortpinion which meshes with said long pinion, a carrier for rotationallysupporting said long pinion and said short pinion, a second sun gearmeshing with said short pinion, and a ring gear meshing with said longpinion; wherein said first rotary component is said second sun gearwhich receives the reduced speed rotation of said reduced speed rotationoutput means; wherein said second rotary component is said first sungear which receives input of rotation from said input shaft when saidfirst clutch is engaged, and which is fixed against rotation byengagement of said first brake; wherein said third rotary component issaid carrier which receives input of rotation of said input shaft whensaid second clutch is engaged, and which is fixed against rotation byengagement of a second brake; and wherein said fourth rotary componentis said ring gear linked to said output member.
 41. An automatictransmission according to claim 40, wherein, in first speed forward,reduced speed rotation is input to said first rotary component from saidreduced speed rotation output means, and said second brake is engaged;wherein, in second speed forward, reduced speed rotation is input tosaid first rotary component from said reduced speed rotation outputmeans, and said first brake is engaged; wherein, in third speed forward,reduced speed rotation is input to said first rotary component from saidreduced speed rotation output means, and said first clutch is engaged;wherein, in fourth speed forward, reduced speed rotation is input tosaid first rotary component from said reduced speed rotation outputmeans, and said second clutch is engaged; wherein, in fifth speedforward, said first clutch and said second clutch are both engaged;wherein, in sixth speed forward, said second clutch and said first brakeare engaged; and wherein, in first speed reverse, said first clutch andsaid second brake are engaged; whereby said automatic transmissionprovides six forward speeds and one reverse speed.